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package java.security.cert;

import java.security.InvalidAlgorithmParameterException;

/**
 * The <i>Service Provider Interface</i> (<b>SPI</b>)
 * for the {@link CertPathBuilder CertPathBuilder} class. All
 * {@code CertPathBuilder} implementations must include a class (the
 * SPI class) that extends this class ({@code CertPathBuilderSpi}) and
 * implements all of its methods. In general, instances of this class should
 * only be accessed through the {@code CertPathBuilder} class. For
 * details, see the Java Cryptography Architecture.
 * <p>
 * <b>Concurrent Access</b>
 * <p>
 * Instances of this class need not be protected against concurrent
 * access from multiple threads. Threads that need to access a single
 * {@code CertPathBuilderSpi} instance concurrently should synchronize
 * amongst themselves and provide the necessary locking before calling the
 * wrapping {@code CertPathBuilder} object.
 * <p>
 * However, implementations of {@code CertPathBuilderSpi} may still
 * encounter concurrency issues, since multiple threads each
 * manipulating a different {@code CertPathBuilderSpi} instance need not
 * synchronize.
 *
 * @author Sean Mullan
 * @since 1.4
 */
public abstract class CertPathBuilderSpi {

  /**
   * The default constructor.
   */
  public CertPathBuilderSpi() {
  }

  /**
   * Attempts to build a certification path using the specified
   * algorithm parameter set.
   *
   * @param params the algorithm parameters
   * @return the result of the build algorithm
   * @throws CertPathBuilderException if the builder is unable to construct a certification path
   * that satisfies the specified parameters
   * @throws InvalidAlgorithmParameterException if the specified parameters are inappropriate for
   * this {@code CertPathBuilder}
   */
  public abstract CertPathBuilderResult engineBuild(CertPathParameters params)
      throws CertPathBuilderException, InvalidAlgorithmParameterException;

  /**
   * Returns a {@code CertPathChecker} that this implementation uses to
   * check the revocation status of certificates. A PKIX implementation
   * returns objects of type {@code PKIXRevocationChecker}.
   *
   * <p>The primary purpose of this method is to allow callers to specify
   * additional input parameters and options specific to revocation checking.
   * See the class description of {@code CertPathBuilder} for an example.
   *
   * <p>This method was added to version 1.8 of the Java Platform Standard
   * Edition. In order to maintain backwards compatibility with existing
   * service providers, this method cannot be abstract and by default throws
   * an {@code UnsupportedOperationException}.
   *
   * @return a {@code CertPathChecker} that this implementation uses to check the revocation status
   * of certificates
   * @throws UnsupportedOperationException if this method is not supported
   * @since 1.8
   */
  public CertPathChecker engineGetRevocationChecker() {
    throw new UnsupportedOperationException();
  }
}
